[Boatanchors] tube markings

[CLIVE COLLINS]

Good day Gentlemen
 
Does anyone herein happen to know why manufacturers of tubes didn't mark the type of the tube (6V6, 807 etc etc) in some form on the anode of the device where it would not rub off and still be visible when the tube was thrown away?
This goes the same for the Eimac ceramic and glass tubes, why didn't they engrave the type on the anode surface?
 
The practice of marking the outside with a low grade paint has always seemed to be a frought method of identification.
 
As this probably might be considered to be a bit wide of topic for the reflector, if it is considered to be then my apologies in advance (but I would still like to know !)
 
regards,
 
Clive GW3WEQ